“…The number of participants in the included RCTs was in the range of 40–1000, and the mean age was between 14.03 ± 1.17 and 22.42 ± 13 years. In six RCTs (Alshammari and Huggare, 2019; Azeem et al, 2018; da Silva Santos and Capelli, 2021; Delavarian et al, 2020; Hamid et al, 2016; Ireland et al, 2016), it was reported that both male and female participants were included; two RCTs (Al Shayea, 2020; Farzanegan et al, 2012) included only female patients, and Elvina et al (2018) did not report the gender of the participants. Five RCTs (Al Shayea, 2020; da Silva Santos and Capelli, 2021; Delavarian et al, 2020; Farzanegan et al, 2012; Hamid et al, 2016) reported that participants had mild to severe dental crowding malocclusion, and four RCTs (Alshammari and Huggare, 2019; Azeem et al, 2018; Elvina et al, 2018; Ireland et al, 2016) did not report the type of malocclusion.…”